OpenCV图像处理——矩形（Rect）类的常用操作

1.Rect类

创建类

Rect类成员变量x、y、width、height，分别为左上角点的坐标和矩形的宽和高。

创建一个Rect对象Rect,并在图像上画该矩形框。

	cv::Rect rect(100, 50, 500, 500);
	cv::Mat cv_src = cv::imread("11.JPG");
	cv::rectangle(cv_src, rect, cv::Scalar(255, 0, 0),4);
	cv::namedWindow("src", 0);
	cv::imshow("src", cv_src);

	cv::waitKey(0);
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2. Rect常用参数

cv::Rect rect(100, 50, 500, 500);

rect.area();//面积
rect.size();//大小
rect.tl(); //左上角
rect.br(); //右下角
rect.size().width;//宽
rect.size().height; //高

std::cout << "rect area = " << rect.area() << ",rect size = " << rect.size()
		<< ",rect tl = " << rect.tl() << ",rect br = " << rect.br() << ", rect width = "
		<< rect.size().width << ",rect height = " << rect.size().height << std::endl;
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输出

rect area = 250000,rect size = [500 x 500],rect tl = [100, 50],rect br = [600, 550], rect width = 500,rect height = 500
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3. 常用判断

3.1 判断点是否在矩形内,就是矩形是否包含这个点

rect.contains(cv::Point(x, y)); 
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3.2 判断对比两个矩形是否相等

rect1 == rect2;
rect1 != rect2;
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3.3 判断矩形是否包含另一个矩形

bool isInside(cv::Rect& rect1, cv::Rect& rect2)
{
	if (rect1.area() > rect2.area())
	{
		return (rect1 == (rect1 & rect2));
	}
	else
	{
		return (rect2 == (rect2 & rect1));
	}
}
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测试调用代码

	cv::Rect rect1(100, 50, 500, 500);

	cv::Rect rect2(150, 100, 300, 300);

	cv::Mat cv_src = cv::imread("11.JPG");
	cv::rectangle(cv_src, rect1, cv::Scalar(255, 0, 0),4);
	cv::rectangle(cv_src, rect2, cv::Scalar(255, 0, 255), 4);
	cv::namedWindow("src", 0);
	cv::imshow("src", cv_src);

	std::cout << isInside(rect1, rect2) << std::endl;

	cv::waitKey(0);
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3.4 判断两个矩形是否相交

当要判断两具矩形是否相交，就要考虑到，两个矩形如果相交几种可能性。

bool computRectJoinUnion(cv::Rect& r1, cv::Rect& r2)
{
    if (r1.area() > r2.area())
    {
        if (r1.contains(r2.tl()) || r1.contains(r2.br()))
        {
            return true;
        }
        else
        {
            return false;
        }
    }
    else if (r1.area() < r2.area())
    {
        if (r2.contains(r1.tl()) || r2.contains(r1.br()))
        {
            return true;
        }
        else
        {
            return false;
        }
    }
    else
    {
        return false;
    }
}

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4.矩形常用操作

4.1 获取矩形矩形中心

cv::Point getCenterPoint(cv::Rect& rect)
{
	cv::Point cpt;
	cpt.x = rect.x + cvRound(rect.width/2.0);
	cpt.y = rect.y + cvRound(rect.height/2.0);
	return cpt;
}
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4.2 缩放矩形

//缩放矩形
//缩放矩形
cv::Rect rectScale(cv::Rect& rect, double scale_factor)
{
	int w_scale = (rect.width * scale_factor - rect.width)/2;
	int h_scale = (rect.height * scale_factor - rect.height)/2;
	cv::Rect new_rect;
	new_rect.x = rect.x - w_scale;
	new_rect.y = rect.y - h_scale;
	new_rect.width = rect.width * scale_factor;
	new_rect.height = rect.height * scale_factor;

	return new_rect;
}
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